未显示所需结果的多处理代码

Question

我试图理解Python中的多处理，并尝试复制以下代码的结果（摘自Corey Schafer youtube视频）。代码正在运行，但多处理模块不工作。我使用的是Windows10和python版本3.8.5，我的笔记本电脑有8个内核

import time
import multiprocessing
import workers4
tic=time.time()

processes=[]
if __name__ == '__main__':
    for _ in range(50):
        p=multiprocessing.Process(target=workers4.do_something,args=[20])
        p.start()
        processes.append(p)
    
    for process in processes:
        process.join()

toc=time.time()
elapsed=toc-tic
print("\nFinished in ",elapsed," seconds")

文件workers4.py具有函数“do_something”，该函数使代码在通过参数传递的特定时间值内休眠

def do_something(seconds):
    print(f "Sleeping {seconds}second(s)...")
    time.sleep(seconds)
    print("Done sleeping...")

在运行上述代码时，它仅显示
在0.8727371692657471秒内完成

并且workers.py文件中的do_something函数中的以下语句一次也没有打印

print(f "Sleeping {seconds}second(s)..."), 
print("Done sleeping...") 

似乎dou_something函数没有像每个进程睡眠时间为20秒那样执行，代码如何在0.8727秒内执行。上述代码中还有50个进程，与for循环一样。有人能帮助解决什么问题以及如何纠正它吗

Answer 1

所以我做了一些改动，运行得很好。更改是我没有worker4.py文件，将等待时间更改为1秒。最重要的更改是将print(f "Sleeping {seconds}second(s)...")行更改为print(f"Sleeping {seconds}second(s)...")，因为f和第一个引号之间的空格导致了语法错误

import time
import multiprocessing
tic=time.time()

processes=[]

def do_something(seconds):
    print(f"Sleeping {seconds}second(s)...")
    time.sleep(seconds)
    print("Done sleeping...")

if __name__ == '__main__':
    for _ in range(50):
        p=multiprocessing.Process(target=do_something,args=[1])
        p.start()
        processes.append(p)
    
    for process in processes:
        process.join()

toc=time.time()
elapsed=toc-tic
print("\nFinished in ",elapsed," seconds")

获得以下输出

Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Sleeping 1second(s)...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...
Done sleeping...

Finished in  1.7538056373596191  seconds